DEV: Add backwards-compatible tag object handling

What is the problem?

Discourse core PR #36678 changes tags from strings to objects
with `{ id, name, slug }` format. The `iconTagRenderer` function
in this theme calls `tag.toLowerCase()` which fails when `tag`
is an object instead of a string.

What is the solution?

Extract the tag name using the same pattern as core's `defaultRenderTag`:
`const tagName = typeof tag === "string" ? tag : tag.name`

This maintains backwards compatibility with Discourse versions before
the change.

discourse/discourse#36678

Author: Discourse CI

javascripts/discourse/initializers/tag-icons.js

@@ -8,14 +8,18 @@ function iconTagRenderer(tag, params) {
   // Get the rendered default tag markup.
   const renderedTag = defaultRenderTag(tag, params);
 
+  // Handle both string tags (legacy) and object tags (new format: { id, name, slug })
+  // This maintains backwards compatibility with Discourse versions before PR #36678
+  const tagName = typeof tag === "string" ? tag : tag.name;
+
   // Get the tag configuration list from the settings.
   const tagIconList = settings.tag_icon_list.split("|");
 
   // Returns the tag configuration if found.
   const tagIconItem = tagIconList.find(
     (line) =>
       line.indexOf(",") > -1 &&
-      tag.toLowerCase() === line.substr(0, line.indexOf(",")).toLowerCase()
+      tagName.toLowerCase() === line.substr(0, line.indexOf(",")).toLowerCase()
   );
 
   // Update the tag markup with an SVG icon, and inline-styles for the colors.

spec/system/tag_icons_spec.rb

@@ -9,6 +9,7 @@
   fab!(:user)
 
   let(:topic_page) { PageObjects::Pages::Topic.new }
+  let(:topic_list) { PageObjects::Components::TopicList.new }
   let(:tag_icon) { PageObjects::Components::TagIcon.new }
   let!(:theme) { upload_theme_component }
 
@@ -28,6 +29,16 @@
     )
   end
 
+  it "displays tag with icon on topics list page" do
+    visit "/latest"
+    expect(topic_list).to have_topic(topic)
+    expect(tag_icon).to have_icon_for_tag(
+      tag_name: "support",
+      icon: "question-circle",
+      color: "#ff0000",
+    )
+  end
+
   it "displays tag without icon when not configured" do
     theme.update_setting(:tag_icon_list, "")
     theme.save!